Automatic telephone system



Aug. 9, 1927. 1,638,513

R. F. STEHLIK AUTOMATIC TELEPHONE SYSTEM Filed Sept. I5, 1925 In' Ue I@WET-T hama Allg. s, 1921.

UNITED STATES PATENT OFFICE.

RUDOLPH l'. BTEELIX. OIOHIOAGO, ILLINOIS, ABBIGNOB, BY ASSI@ TO AUTOITIOBLBOTBIO INC., 0l' CHICAGO, ILLINOIS, A CORPORATION Ol' Dm AUTOIAIIOTELEPHONE SYSTEM.

Application led September 8, 1925. Serial lo. 54,188.

two directional type of rotary connector re sponds to two digitstransmitted to it, the first digit positioning the wipers opposite thelevel of bank contacts in which the desired group of trunks is located,while the second digit positions the wipers on the first `bank contactof the desired group. The switch then automatically rotates its wipersuntil the engage contacts with which an idle trun is associated. If alltrunks are bus the switch continues to rotate until it arrives at thelast bank contact of the group and then transmits thel busy tone to thecalling subscriber.

`The ordinary two directional type of switch has access to ten levels,each comprising ten contact sets and, therefore, this arln rangementWorks ve nicely where the trunk groups are ma e up of ten or lesstrunks. In cases where rivate branch exchanges are of such capacity thatten trunks are insuflicient to take care of the traflic the branchexchange is given two directory numbers. This is objectionable in thatif a subscriber desires to connect with the branch exchange it may benecessary to dial both directory numbers owing to the fact that thefirst group of trunk lines by way of which the subscriber attempted toattain access to the private branch exchange was busy.

In a Wicks Patent No. 1,603,929, patented October 19, 1926, thisobjectionable feature 46 was overcome by adding vertical test equipmentand by modifying the rotary connector circuits so that when grou s ofover ten trunks were desired the switc was arranged to move its wipersfrom the level to which they were operated directively to the next levelin case all trunks in the first level were busy. The resent invention,however, overcomes the obJectionable feature by merely switchinvr fromone set of wipers to another, whic method in some installations hasproved the more desirable.

The present invention also enables the assignment of highly desirabledirectory numbers to large branch exchanges using more than ten trunks.In the connectors formerly used, as previously stated, the connectorswitches o crate responsive to two digits, the first digit ein utilizedto elevate the wipers to particular evel and the second digit beingutilized to position the wi ers into engagement with the contacts of t efirst trunk of a desired group. In the present disclosure in callintrunk groups comprising less than ten trun s, the operation is the sameas formerly. If, however, the trunk group exceeds ten, the last digitmay be selected to suit the whim of the private branch exchangesubscriber, as this digit is not necessary and is absorbed.

The accompanying drawing shows suiicient of a telephone system to enablethe invention to be intelli ently described. More specifically thedrawing discloses a connector of the `well known vertical and rotarytype with the circuits modified in accordance with the invention. Theshaft (not shown) caring the usual wipers is, of course, also e ongatedto provide the necessary space for the added Wipers which are necessaryto the carrying out of the invention.

In order that a thorough understanding of the invention may be had, adescri tion will first be given of the manner in whic the connectionsare'set up from the calling station to a private line and to a tprivatebranch exchange trunk line terminating in a group comprising less thanten trunk lines, respectively, after which it will be explained how anyone of twenty trunks may be selected.

The usual subscribers substation, individual line switch and selectorswitches used by a subscriber in completing a connection being wellunderstood by t ose skilled in the art and since this equipment forms nopart 100 of the invention, it is believed it will suffice to say thatthe calling subscriber upon removin v the receiver from the switchhookcauses his line switch to extend the calling line conductors intoconnection with an idle selector. The subscriber then operates hiscalling device in the usual manner causing his line to be extended to asecond selector or to a connector such as the connector E, depending onthe capacity of the system.

Let us assume that the calling subscriber has set up the connection asfar as the last selector and that the wipers of that selector have cometo rest on the bank contacts, which are connected to conductors 23, 24,and 25, resulting in the switching relay of the selector completing anenergizing circuit for the line relay 26 of the connector E. The linerelay 26 upon energizing in turn causes the energization of slow releaserelay 28. Relay 28, in operating at its armature 39 supplies ground tothe release trunk conductor 24 to maintain the previously operatedswitches operated in the usual and well understood manner. Relay 28 atits armature 38 prepares holding circuits for various relays as will beexplained hereinafter and at armature 37' prepares a circuit forvertical magnet 40 and slow release relay 29.

We will first assume that the last two digits of the desired subscribersnumber are 1 and 9, respectively. The subscriber, therefore, dials thedigit 1 causing line relay 26 to drop back momentarily to transmit animpulse by way of its grounded armature and resting contact, armature 37and its working contact, ofl'I normal spring 88 and its resting contactand the winding of relay 29 and vertical magnet 40 to battery. Thevertical magnet functions in the usual manner to elevate the wipers 7 4to 81, inclusive, a number' of steps corresponding to the number ofimpulses transmitted to the line relay 26, which in the present case wasl, and causes the operation of the ott normal springs 87 and 88.

Shortly following the transmission of the impulse to vertical magnet 40,slow release relay 29 restores and at its armature and back contactprepares an operating circuit for slow release relays 33, 34, and therotary magnet 42. Responsive to the dialling of the digit 9, the linerelay 26 causes nine impulses to be transmited from its groundedarmature and back contact, armature 37 and its working contact, springscontrolled by off normal spring 88, armature of relay 29 and its backcontact, back contact and armature 48, the windings of relay 33 inmultiple to point 100, where the circuit divides, one branch extendingby way of the back contact and armature 53 to the winding of slow relay34 and battery; the other branch extending by way of armature 62 `ceptthe last line of the group.

and its resting contact and the rotary magnet 42 to battery.

Relays 33 an 34 are slow to release and,

therefore, although the circuit of relay 34 is transferred, upon theenergization of relay 33, from that just traced so that it obtainsground direct from armature 53 and the Working contact of relay 33, thisrelay does not deenergize until following the deenergization of slowrelease relay 33, which also remains energized until an interval afterthe entire series of impulses have been transmitted to the rotary magnet42. Relay 34 at its armature 57 and its working contact connects thetest wiper into electrical connection with the winding of test relay 32.Relay 33 at its armature 56, completes a circuit around armature 48 andits resting contact so as to avoid the im ulsing circuit being interruted should t e test relay be operated whi e wiper 75 is passing overbusy or rounded test contacts.

Assuming t at the desired line is busy at the present time, there willbe a ground potential present upon the test control 101 engaged by thetest wiper 7 5 and the test relay 32 will be energized. Relay 32 uponoperating at its armature 52 prepares a locking circuit for itself whichis completed upon the deenergization of slow acting relay 34, and at itsarmature 73 places a busy tone on the lower heavy talking conductorwhereby the calling subscriber is notified that the desired line isbusy. The calling subscriber will accordingly replace his receiver uponthe switchhook thereby initiating the release of the operated switches.

It will non.r be assumed that the line of the desired substation is oneof a group of trunk 'lines listed under the same directory number, forinstance, it may be assumed that the last two digits of which is 21. Inthis case the circuits of the connector E must be slightly changed inorder to enable it to select therfirst idle one of these lines. This isaccomplished in the usual manner by connecting the test contacts 92 and93. similar to test contacts 101 and 102, together on all ex- UnderthescJ conditions when a line becomes busy, ground is present upon boththese test contacts. As shown the 'test contacts 92 and 93 and the threesubsequent sets of test contacts are so connected. Now, if it is assumedthat the first trunk Was busy when connection was attempted, the testrelay 32 will become energized as before described and will operate andprepare a locking circuit for itself at its armature 52 as before, andin addition, since contacts 92 and 93 are tied together. at its armature51 prepares an operatingr circuit for stepping relay 31 which is comleted iinmediately upon the restoration o relay This circuit forstepping relay 31 extends by way of grounded wiper 74, resting coutactand armature 68, workin contact and amature 58, armature 51 an itsworking contact, resting contact and armature 54. interrupter springs ofrotary magnet 42 and the winding of relay 31 to battery. Relay 31 uponoperating' at its armature 45 and its working contact completes alocking circuit for itself, and at armature 46 and itsworking contactprepares a locking circuit for slow release relay 34 which will becompleted immediately upon the restoration of slow release relay 33. Abranch of the circuit` for relay 34 also includes a new circuit for therotary magnet 42 extending from the grounded spring controlledbyarmature 53, Working contact and armature 46, armature 62 and itsresting contact and the winding of rotary magnet 42 to battery. Uponcomp'letion of this circuit rotary magnet 42 bccomes energized and atits interruptor sprin s opens the circuit of stepping relay 31, W ich,ipon energizing at its armature 46, opens the circuit of rotary magnet42. causing this magnet to deenergize. The alternate operation ofstepping relay 31 and rotary magnet 42 now continues to take place aslong as grounded test contacts 92 are engaged.

If all of the lines of the group are busy, since the last test contactset similar to 92 and 93 are not tied together, there will be no groundpotential present on the test contact engaged by the test wiper 74. Thetest relay 32 will, therefore. be the only relay operated and no furtherrotary movement can take place, instead the busy tone will be given tothe calling subscriber in the same manner as was described in the casewhere a subscribers line was called.

It will now be assumed that the first line of the group was idle whenconnection was attempted therewith by the connector E. Under vthesecircumstances there will be no ground potential present upontest-,contact engaged by wiper 75 and, therefore, no circult iscompleted for test relay 32, or stepping relay 31. Accordingly,followingr deenergization of slow release relay 34, a circuit iscompleted extending from grounded working contact and armature 39,armature 52 and its resting contact, upper winding of switching-relay35, resting contact and armature 57, armature 69 and its restingcontact. test wiper 75 to battery supplied through the winding of themotor magnet of the incoming individual line switch associated with theline for extending connections to the branch exchange. Relay 35, uponenergizing, at its amature and its' working contact completes a lockingcircuit for itself by way of armature 38 and its 'grounded workingcontact, opens a point in the operating circuit of wiper switching relay36 at its armature 66, at its armature 64 opens a point in the operating'circuit of busy relay 32, at its armature 63and its working contactconnects direct ground to the private wiper 75 to render the 'line busyto other subscribers, at its armature 60 and 60'A connects interruptedgenerator and ground, respectively, to the line conductors by way ofwipers 78 and 79, at armature 62 opens a point in the operating circuitof rotary niagnet 42 and at armature 61 cuts in a low capacity condenserin the upper conductor so that the calling subscriber may hear thesignaling'operation take place.

When the called subscriber or attendant operator of thev rivate branchexchange answers, a circuit fdr the ring cutoff relay 30 is completedover the called loop. Relay 30, upon energizing, establishes a lockingcircuit for itself at its armature 43 in multiple with that describedfor the switching relay 35 and at its armature 44 and 47 cuts oft'generator and ground, respectively, from the conductors of the callinline and connects these conductors throng to finally complete thetalking connection. The back bridge relay 27 is immediately energizedover the line of the substation ory attendant operators equi ment andsuppliestalking current to tllie called subscriber, and at its armature10S and working'eontact connects ground to the holding conductor 105 soas to maintain the connector E operated as long as either thc calling orcalled line has his receiver oli the hook.

We will now assume that connection is desired with a private branchexchange over any of twenty trunks available to the connectorJ),orslmilar switches, but before proceeding with this description it. isconsdered advisable to briefly explain the manner in which the switch isarranged to accomplish this result without increasing its capacity. Inillustrating the invention it will be assumed that the particular branchexchange in question has been given the desirable directory numberl of5000 and, therefore, when the first digit 0 is transmitted to the counector the wipers 74 to 81, inclusive, will be elevated ten steps. Thewiper 76-77. and 80-81 are located six steps or levels below therespective wipers 74-75 and 78h79 so that when digit 0 is dialed and thewipers 74-7 5 and 78--7 9 are opposite the 0 or tenth level of the bankcontacts, wipers 76-77 and 80-81 are opposite the fourth level of bankcontacts. From this it will be appreciated that the twenty trunksavailable in the present instance are the 10 located in the tenth leveland the 10 located in the fourth level of the switch E. Since the numberof rotary steps or the number of trunks in any one level is limited toten. the tenth bank contact in each instance that is, in the 0 level andin the fourth level, are not multipled. The remaining private contactsof the entire group are multipled or' joined together in the same manneras was explained inconnecton with trunk groups of less than ten.Connected with each test contact of the 0 level, such as thatcorresponding to 93 of the 0 level, are chain relays and the circuitsare so arranged, as will subsequently be described, tliat if, when theswitch is elevated to the 0 level, all trunks in that level are busy,the conductor 86 will be grounded, normal post spring will be closed anda circuit will be completed for wiper switching relay 36. This relaywill then be locked up and trunk selection will take place on the fourthlevel in the same manner as if there were only ten trunks available tothe branch exchange.

The operations which take place in the selection of a trunk of a largegroup, as" briefly described in the foregoing will now be described indetail. The connector E is seized in the previously described manner andthe switch operated responsive to the transmission of the digit 0 tostep its associated wiper sets to the tenth and fourth level,respectively. The switch upon taking its tenth step operates shaftsprings 50, 55, and 70. The closure of the springs 50 prepares a pointin the circuit of wiper switching relay 36, the opening of springs opensthe low resistance path to the lower winding of slow release relay 33,while the .springs 0 prepare a point in a new operating circuit forstepping relay 31.

Upon the next and final digit 0, being transmitted to the connector E,relavs 33 and 34 operate in the manner formerly described. Relay 33,however, in this instance, due to the operated condition of normal postsprings 55 is energized through its high resistance winding, whichprevents the impulses operatively aifecting rotary magnet 42. At thistime, since normal post springs are also closed, as soon as armature 54operates, a circuit is completedfor the stepping relay 31 by way ofgrounded armature 63 and its resting contact, normal post springs 7 0,Working contact and armature 54. interrupter springs of rotary magnet 42and the winding of stepping relay 31 to battery. Shortly following thetransmission of the last impulse relay 33 restores and at springscontrolled by armature 53 completes the previously described circuit forrotary magnet 42. The operation from this point depends on whether allthe trunks in the 0 level are busy or not. If any one trunk is idle noground will be'present on conductor 86, the operation of normal postspring 50 will be without effect and the switch will operate to causethe selection of an idle trunk in the 0 level in the same manner asdescribed when trunk selection took place in the second level.

lf, however, all the trunks of the 0 level are in use, the conductor 86will be grounded by the chain relays 11k-120 and as a result of theclosure of normal post springs 50, a circuit will be completed by way ofarmature 49 and its back contact, back contact and armature 66, andsprings controlled by armature 71 for the wiper switching relay 36,which will immediately operate. Relay 36 at its armatnrer71 completes alocking circuit for itself and at armature 67, 68, 69, y

and 72 switches the various conductors of the switch E from connectionwith the wipers normally used to the auxiliary wipers 76-77 and 80-81,which as previously explained are op osite the fourth level of theirrespective ban s. The trunk selecting operation is not changed by theswitching 0f the wipers and takes place in the same manner as describedin the foregoing.

It will be assumed that the twentieth trunk, the tenth trunk of thefourth level, is the only trunk idle. When the wipers 7 6 and 77 reachthe test contacts with which this trunk is associated, no ground beingpresent on test Contact 121, busy relay 32 will not be energized, butfollowing the deenergization of slow release relay 34 the previouslydescribed circuit for switching relay 35 will be completed resulting inthe connection previously described.

When the conversation is terminated both the subscribers will replacethe receivers upon their respective switchhooks. When the receiver isreplaced at substation A, the circuit for line relay 26 and slow releaserelay 28 will be opened. The deener 'zation of relay 28 causes thecalling subscri rs line switch and any intervening selector switches tobe restored to normal and also causes ground to be removed from onepoint of conductor 105, to prepare the circuit for release magnet 122.The switch E is not released, however, until both parties have restoredtheir receivers owing to the fact that the release magnet circuit isstill open at armature 109 of the back brid e, relay 27, and the holdingconductor 105 or the various relays of the switch E is maintainedgrounded by armature 108 and its working contact. When the calledsubscriber replaces his receiver the back bridge relay, however,

being completed in the manner restores to normal causing the releasemagnet circuit to be completed and the holding circuit for relays 30,36, and 35 to be opened, these relays and the switch E accordinglrestore to normal, rendering the trunk avai able for further calls.

In the foregoing description it was assumed that the entire maximum oftwenty trunks were utilized as a single grou In many cases a smallernumber of trunhs are suilicient. For instance, 'in the case illustratedthere mi ht have been only the first five trunks avai able to theauxilia wiper set in the fourth level, the remaining ve fill contactsets being utilized as another trunk Uroup accessible to the regularwiper set. urtherinorc, if, the re ular wiper set has rovided below itauxi iary wipers located ve steps below them instead of six, asillustrated, the switch may be utilized to connect with any of livegroups of over ten trunks each and also be able to select any one offive ormore groups comprising less than ten trunks. in which case itwill be understood that the small trunk groups would be located in therighthand portion of the live lower bank contact sets and be selectableonly by the regular wiper set. In such an arran ement the normal postsprinvs 50, 55, and 0, instead of operating on tlie 0 level only, wouldoperate on the sixth toteiitli or 0 level inclusive.

From the foregoing it will be appreciated that applicant has desiriied arotary connector having features ighly desirable in cci-tain instancesover former switches of this type.

What is claimed is:

1. In a telephone system, a connector switch havin two sets of wipers, aplurality of levels of bank contacts accessible to said wiper sets.means for directively operating said switch to cause each of said wi ersets to be positioned opposite a different evel of bank contacts, meansfor causing said' wipers to successively engafre all the contacts in thelevel opposite which they have been positioned, lines terminating insaid bank contacts, means for making said lines busy, means normallycausing only one set of wipers to test for an idle line as itsuccessively engages its bank contacts, and means for causingr only theother wiper set to test if all lines available to the first wiper arebusy.

2. In a telephone system, a connector having two sets of wipers, linesdivided into groups and subgroups accessible to one of said wiper setsonly, and other lines divided into groups and subgroups accessible toboth wiper sets, means for directivel operating said connector in aprimary irection to select a group of lines available to one of saidwiper sets, and means eilective in case all lines in said group are busfor rendering the other wiper set availab e to select an idle line of asecond group.

S. In a telephone system, an automatic switch ot the two directionaltype, a plurality of wiper sets. a bank of contacts dividcd into aplurality Iof groups, lines terminating at. said contacts, directivecontrolled means for elevating one of said Wiper sets opposite one groupof said contacts and for simultaneously moving the other wiper setopposite a second group of contacts, means for causing said switch tomove both wiper sets to select an idle line of a group and automaticmeans effective after the directive automatically test for ani e trunkin ono of said groups responsive to any digit im pulse or impulsestransmitted to it, and means effectiyjfonly in case all trunks in onegroup aile'busy for causing the lines in the other grou to be tested.

5. In a telep one system, a rotary connector switch, lines accessible tosaid switch, said switch responsive to a series of impulses to cause theselection of a particular group of said lines, means subsequentlyresponsive to only one impulse of a subsequent impulse series to causeone of the lines ot' the selected group to be connected withirrespective of the busy oil idle condition of the first lines in theselected group and means in said switch for absorbing the remainingimpulses of the last impulse series.

6. In a telephone system a connector switch, groups of lines terminatingin bank contacts ot' said switch. said switch responsive to one or moreseries of impulses to se-Y lect a group of lines and means automaticallyresponsive to cause the switch to select an idle line of the selectedgroup where the selected ffroup requires more than one series ofimpulses and responsive to an impulse of a second impulse seriesirrespective of the number ot' impulses in the latter series to causethe switch to select an idle line of a group selected b one impulseseries.

7. In a teleplione system, an automatic 'switch having normallyellective and normally ineffective Wiper sets respectively, a

lurality of levels of contacts each level having contacts accessible toonly one of said wiper sets, other levels of contacts each having acontact available to both wiper sets and means for reversing the statusof said wiper sets automatically after the selection of the level.

8. In a telephone system, an automatic switch of the two directionaltype, a plurality of wiper sets, lines terminating at said contacts,directive controlled means for elevating one of said wiper sets oppositeone group of said contacts and for simultaneously moving the other wiperset opposite a second grou of contacts, means for causing said switc tomove both vwiper sets to select an idle line of a group and automaticmeans effective after the directive movement for determining which Wiperset will be used.

9. In a telephone system. an automatic switch of the two directionaltype, a plurality of wiper sets, a bank of contacts divided into aplurality of groups, lines terminating at that contact, directivecontrolled means for elevatin one of said wiper of said directivecontrolled means for desets opposite one group o said contacts andtermining which wiper set will be used. for simultaneously moving theother wiper In witness whereof, I hereunto subscribe 10 set opposite esecond grou of contacts, my name this 31st day of August, A. D.,

l means for causing said switc to move both 1925.

wi. r sets to select an idle line of a. group, an automatic meanseffective independent RUDOLPH F. STEHLIK.

6 I 1,ess,s1s

trolled means for elevatin one of said wiper of said directivecontrolled means for desets opposxte one group o said contacts andtermining which wiper set will be used. for slmultaneously movIng theother wiper In witness whereof, I hereunto subscribe 10 set opposite asecond grou of contacts, my name this 31st day of August, A. D., l meansfor causing said sWItc to move both 1925.

wier sets to' select an idle line of a group, an automatic meanseffective independent RUDOLPH F. STEHLIK..

CERTIFICATE oE CORRECTION.

Patent No. 1,638,513. Granted August 9, 1927, to

RUDOLPH F. STEHLIK.

It is hereby certified that error appears in the printed specificationof the above numbered patent requiring correction as follows: Page S,strike out lines 114 t0 130, and page 6, lines l to 9, comprising claims8 and 9, and insert the following as claims 8 and 9:-

8. In a telephone system, an automatic switch having two wiper sets,means for moving said wiper sets simultaneously, a plurality of levelsof contacts available to both wiper sets but available to one wiper setbefore any level becomes available to the other wiper set, and anotherplurality of levels of contacts available only to one of said wipersets.

9. In a telephone system, a connector switch, groups of linesterminating in bank contacts of said switch, said switch responsive toone or more series of impulses to select a group of lines, meansautomatically7 effective after a group has been selected by more thanone series of impulses for causing it to automatically initiate its lineselecting movement, means for preventing the initiation of the lineselecting movement where the group is selected by one impulse series,and impulse controlled means for causing the line selecting movement tobe initiated in the latter instance.;`

and that the said Letters Patent should be read with this correctiontherein that the same may conform to the record of the case in thePatent Office.

Signed and sealed this 19th day' of June, A. D. 1928.

. M. J. Moore, (Seal) Acting Commissioner of Patents.

CERTIFICATE 0F CORRECTION.

Patent No. 1,638,513. Granted August 9, 1927, t0

RUDOLPH F. STEHLIK.

It is hereby certified that error appears in the printed specificationof the above numbered patent requiring correction as follows; Page 5,strike out lines 114 to 130, and page 6, lines 1 to 9, comprising claims8 and 9, and insert the following as claims 8 and 9:-

8. In a telephone system, an automatic switch having two wiper sets,means for moving said wiper sets simultaneously, a plurality of levelsof contacts available to both wiper sets but available to one wiper setbefore any level becomes available to the other wiper set, and anotherplurality of levels of contacts available only to one of said wipersets.

9. In a telephone system,V a connector switch, groups of linesterminating in bank contacts of said switch, said switch responsive toone or more series of impulses to select a group of lines, meansautomatically effective after a group has been selected by more than oneseries of impulses for causing it to automatically initiate its lineselecting movement, means for preventing the initiation of the lineselecting movement where tbe group is selected by one impulse series,and impulse controlled means for causing the line selecting movement tobe initiated in the latter instance.;

and that the said Letters Patent should be read with this correctiontherein that the same may conform to the record of the case in thePatent Office.

Signed and sealed this 19th day of June, A. D. 1928.

M. J. Moore, (Seal) Acting Commissioner of Patents.

